Acoustic device



l May 7, 1935.

'//vvE/voR J. R. E RIC/(SON J. R. ERICKSON ACOUSTIC DEVICE Filed Jan. l0, 19254 ATTORNEY Patented May 7, 1935 MTI-:Nr OFFICE ACOUSTIC DEVICE John R. Erickson, Orange, N. J., assignor to Bell Telephone Laboratories,

Incorporated, New

York, N. Y., a corporation of New York Application January 10,

10 Claims.

This invention relates to acoustic devices and more particularly to a bone conduction telephone receiver.l

An object oi this invention is to improve the elciency andl operating characteristics of the bone conduction type receiver.

One feature of this invention comprises a receiver having a bone actuating member supported by a pair of spaced resilient members.

A further feature comprises such a receiver in which the magnet structure is clamped between the resilient members.

A telephone receiver in accordance with this invention comprises, preferably, a pair of nonmagnetic frame members supporting a pair of straight bar permanent magnets in spaced relation, a pair of pole pieces preferably T-shaped, the ends of the magnets engaging the ends o'f the cross bars on the'pole pieces, the tails of the pole pieces being bent at an angle to provide cores for an energizing winding. An armature is supported in spaced relation to the pole pieces being secured to the center of a resilient spring or restoring member preferably a Z-shaped strip of spring metal. A similar resilient member is clamped between the magnet structure and one frame member. A vibrations conducting rod is secured at each end to these resilient members and is provided at one end with a button-shaped member adapted to be placed against .the bony portions of the users head, preferably against the mastoid eminence. A suitable casing having an aperture through which the button extends provides an enclosure for the structure.

A more complete understanding of this invention will be obtained from the detailed description which follows, read with reference to the appended drawing, wherein: A

Fig. 1 is a sectional view of an acoustic device embodying this invention;

Fig. 2 is a sectional view of the same device along the line 2-2 of Fig. 1;

Fig. 3 is aplan view of the device of Fig. 1 along the line 3-3 thereof with the cover member removed;

Fig. 4 is a perspective view of a fragment of the device of Fig. l, partly exploded and partly broken away; and

Fig. 5 illustrates how the acoustic device shown by Figs. 1 to 4 is used.

'I'he 4acoustic device herein disclosed comprises a bone conduction receiver designated generally as I8. This receiver comprises a casing or enclosure II, preferably of insulating material.

1934, Serial No. 706,021 (Cl. T39-107) having a substantially flat or planar wall portion I2 containing an aperture I3, and having a substantially rectangular open end normally closed by a cover, plate or removable wall member I4 secured to the casing rim I5 by any suitable means, for instance, screws I6. The casing contains a pair of non-magnetic frame members I1, I8. Frame member I1, preferably of insulating material, comprises a substantially tlat or planar portion I9 and a vertically projecting end portion in which terminal members y2 I are embedded.' The member I1 supports a pair of T-shaped pole pieces 22, for'instance, of magnetic iron, the tail portions 23 of which are bent at an angle to the cross-bar portions 24 to provide cores 25 for an energizing winding 26 comprising coils 21. The free ends 28 of the energizing winding are terminated at the screwmembers 29 which thread into the terminal members 2I. The receiver is connected with an elec- 20 trical signaling circuit through the conductors 30, the tips 3I of which make a force t engagement with similarly shaped passages in the terminal members. A pair of straight bar permanent magnets 32, preferably of cobalt steel, have their end portions resting on the extremities of the cross bars 24, one magnet being on e'ach side of the pole pieces. The frame member, for instance, ofaluminum, rests on the magnetswhich, with the pole pieces, are clamped between .the members I1, I8, for instance, by screw members 33 which extend through the member I1, openings 34 in the pole pieces and thread into tapped drilling 35 Ain the member I8.

A resilient, spring or restoring member 36, for instance, of phosphor bronze and substantially Z-shaped, having strip end portions 31 secured, for instance, by screws 38, to ange end portions 33 of member I8 and a substantially diagonally disposed curved strip portion 40 connecting the strip end portions supports an armature 4I of magnetic material, for instance, magnetic iron, substantially at its mid-portion and in spaced relation to the pole faces 42 of the pole pieces. 45

A similarly shaped resilient member 43 is clamped between frame member I 1 and the pole pieces, the diagonally disposed portion thereof, however, curving in direction opposite to that of portion 40.

A vibrations conducting rod or elongated member 45 connects the resilient members 36, 43 `and has a threaded end portion 46 extending into an opening 41 in the frame member' I1 in alignment with the aperture` I3. A member. 55

preferably at the mastoid eminence, and vcom-1 prisinga fiat enlarged' button-shaped portion I9 andv a cylindrical stub portion 50 is provided with a tapped drilling 5I for engagement with the rod end portion It.

lThe bone conduction receiver Il is. mounted behind the ear with the member 4l resting against the mastoid eminence and may be supported on the head, as illustrated by Fig. 5, by a strap or other member 52, for instance, of spring metal.

Although this invention has been disclosed with reference to a single embodiment, it will be understood that various modifications thereof may be made without departing from the scope of this invention which is to be considered .as limited by the appended claims only.

member attached to said rod near its bone contacting member. "2. An acoustic device comprisingframe members, a magnet structure comprising a pair of straight bar permanent magnets and a pair of T-shaped pole pieces clamped between said framel members, an energizing winding on said pole pieces, a pair of spring members on opposite sides of saidmagnet structure, an armature carried by one of said spring members in spaced relation to said pole pieces, a vibrations conducting rod extending between and secured to said spring members, and means secured to one end of said rod for engagement with the head bones 'of a user.

3. A bone conduction receiver comprising an armature, means for actuating said armature, resilient means supporting said armature, other .resilient means in spaced relation to said rst mentioned resilient means, said resilient means comprsing substantially Z-shaped strips oi' spring metal, and means connecting said resilient means, the means connecting said resilient means being joined thereto substantially at the mid-portions of the strips.

4. A bone conduction receiver comprising an armature, means for actuating said armature, resilientlmeans supporting said armature, said resilient means comprising parallel strips of spring metal, one end of each of which is joined by a substantially diagonally disposedgstrip of spring metal, and means movable with said armature and resilient means for engagementA to be placed in contact with the head,of a user,

secured to said rod for engagement with the head bones of a user.

6. A bone conduction receiver comprising an armature, a magnet structure comprising a pair of straight bar lpermanentmagnets, and a pair of T`shaped`pole pieces, the cross bar of each pole piece engagingone end of each bar magnet and thetail of each pole piece being bent at an angle to the cross bar thereof, an energizing winding surrounding the bent portions of said pole pieces, and a vibrations conducting member for engagement'with the head bones of a user, said conducting member being movable with said armature.

7. A bone conduction receiver comprising, a casing having an aperture in one wall and provided with a cover member, and a unitary assembly in said casing comprising an L-shaped support of insulating material, a Z-shaped spring member on the horizontal portion of said support, a pair of T-shaped pole-pieces, the cross bars thereof resting on the parallel end portions of the spring member and the tails thereof being bent at right angles to the spring member, an energizing winding surrounding said bent portions of the pole-pieces, a pair of straight barpermanent magnets resting on the bars of the pole-pieces, one on each side of the pole pieces,- a frame 4member of non-magnetic ma- I terial mounted on said magnets, fastening meansA i'vor securing together said support, spring members, pole-pieces, ymagnets and frame member, a second and similarly shaped spring member fastened to said frame member, an armature secured at the mid-portion of said second spring member in spaced relation to said pole-pieces,v

and a rod member terminating in a.v buttonshaped portion positioned in the aperture in the casing wall and being secured near opposite ends to said spring members.

8. A bone conduction receiver as claimed in the preceding claim in which terminal members armature, a magnet structure comprising a pair of straight bar permanent magnets, a pair of pole-pieces, each having angularly disposed portions, like portions of each pole-piece being adjacent one end of a bar magnet, an energizing winding on said pole-pieces, and a vibration conducting member for engagement with the head of a user, the armature and the conducting member being secured together.

10. An acoustic device comprising a magnet, pole-pieces, an energizing winding, an armature,

a resilient member supporting said armature in spaced relation to said pole-pieces and having a curved diagonally disposed portion to the mid portion of which said armature is aiiixed, a vibrations conducting rod connected at one end to said armature and having a bone contacting,

member at its other end, and a second resilient member attached to said rod near its bone contacting member, having a curved diagonally dis.

posed portion to the mid portion of which the rod is attached and curving in direction opposite that of the curved portion of the first-mentioned resilient member.

' JOHN R. ERICKSON. 

